A driver who was allegedly being forced at gunpoint to take a stranger to the West Coast raised the alarm by alerting staff at a Christchurch service station.
Police soon tracked down the car and a 29-year-old man was arrested "without incident" at Lake Lyndon.
The alarm was raised by staff at a Christchurch service station at 1.47pm, who told police that a customer said he was being forced to drive to the West Coast by a man with firearms.
After an extensive search, the vehicle was found on SH73 and followed by Christchurch police, before the arrest at Lake Lyndon.
A number of firearms were found in the car.
Police said it was understood the arrested man - who is now being returned to Christchurch for questioning - and the male victim did not know each other.
Police said the investigation was in its very early stages and they were working to understand exactly what occurred.